European Patent EP 1 348 143 describes a radiation emitting device that comprises a radiation emitter, a waveguide, and a parabolic mirror placed between the radiation emitter and the waveguide.
Further radiation emitting devices with parabolic mirrors are disclosed in Japanese Patent Applications JP05113526A and JP 2003262763A.
U.S. Patent Application US 2010/0243870 describes a radiation emitting device that comprises a radiation emitter, a waveguide, and a lens placed between the radiation emitter and the waveguide.